I had an emergency c/s and have been breastfeeding my DS for over 2 months now. There were a few early attachment issues, but I don't think that had anything to do with the c/s. The worst with the c/s was that I didn't get to hold bub until 2 hours after he was born so I missed out on that skin-to-skin contact straight after birth.
Also, my milk came in on Day 2, so no delay there with having a c/s.